Sodium percarbonate has been used for many years in commercial slaughter operations as a bleaching agent for cleaning tripe. Techniques for cleaning tripe are described in U.S. Pat. No. 3,958,304 to Barbee; Perryman and Nassif, "Influence of Processing Techniques on the Final Quality of Tripe." J. Assoc. Publ. Analysis, 1981, vol. 19, pages 95-100; and Skurray and Perryman, "The Effects of Alkaline Hydrogen Peroxide Treatment on the Nutritional Value of Tripe," Meat Science, 1980, vol. 4, pages 313-318.
Sodium percarbonate is available from Birko Corporation under the name ACTO-140.TM. and is approved by the United States Department of Agriculture for use in cleaning tripe, beef feet, beef ears, beef tendons, for bleaching laundry, for use in shroud whitening, and as a bleach for grease and tallow. The ACTO-140.TM. product is available as a solid, oxygen bleach, including about 99.5% by weight sodium carbonate peroxyhydrate (referred to as sodium percarbonate), and about 0.5% by weight sodium carbonate as an impurity. Sodium percarbonate has the chemical formula Na.sub.2 Co.sub.3 .multidot.1.5H.sub.2 O.sub.2.
Processes for treating animal products using sodium percarbonate are described, for example, in U.S. Pat. Nos. 3,025,166 and 3,475,179 to Smith, and assigned to Birko Chemical Corporation.
Hydrogen peroxide has been classified, at least since 1986, as GRAS (generally recognized as safe) for use as a direct human food ingredient. Hydrogen peroxide, alone or in combination with sodium carbonate, has been researched as an antimicrobial agent. Biemuller et al., Journal of Food Science, vol. 38, 1973, pages 261-263, describes the use of a 5% solution of hydrogen peroxide to reduce the bacterial load on inoculated pork carcasses by 2 log. In the study, the bleaching action of hydrogen peroxide caused an unacceptable appearance of the pork skin. A 5% solution of hydrogen peroxide has been proven effective at reducing the bacterial load on beef carcasses. See Gorman et al., Journal of Food Protection, vol. 58, August 1995, pages 899-907; and Cabedo et al., Journal of Food Protection, vol. 59, no. 12, 1996, pages 1284-1287. The logarithmic reduction effect of hydrogen peroxide is minimized as the water temperature is increased to 74.degree. C. It is believed that the hot water does not reduce the effectiveness of hydrogen peroxide but that the scalding effects of water is additionally responsible for killing bacteria. This effect has been found for other decontamination agents including trisodium phosphate and acetic acid. Lillard and Thomson, Journal of Food Protection, vol. 48, 1983, pages 125-126, investigated hydrogen peroxide as a bactericide in poultry chiller water. Total plate count and E. coli numbers were reduced by 95-99% when hydrogen peroxide values were equal or greater than 6,600 ppm. As in the aforementioned pork carcasses study, the appearance of the poultry carcasses was unacceptable due to the bleaching action. Fletcher et al., Poultry Science, vol. 72, 1993, pages 2152-56, describe the use of a 2% sodium bicarbonate rinse solution followed by a rinse with 3% hydrogen peroxide to remove bacteria from poultry carcasses. See U.S. Pat. No. 4,683,618 to O'Brien. The logarithmic reduction in total plate count was less than one.